Zaltoprofen is known as a pharmaceutically active compound which shows excellent anti-inflammatory effect as well as excellent analgesic effect.
Japanese Patent Provisional Publication No. 55-53282 describes a process for preparing Zaltoprofen which comprises hydrolyzing ethyl 5-(.alpha.-cyanoethyl)-2-phenylthiophenylacetate to give 5-(.alpha.-cyanoethyl)-2-phenylthiophenylacetic acid, subjecting the resulting compound to cyclization and amidation of cyano group, and hydrolyzing the amide group of the resulting compound.
Japanese Patent Provisional Publication No. 57-106678 describes an improved process for preparing Zaltoprofen which comprises hydrolyzing ethyl 5-(.alpha.-cyanoethyl)-2-phenylthiophenylacetate to give 2-(3-carboxymethyl-4-phenylthiophenyl)propionic acid and cyclizing the resulting compound in the presence of a condensation agent.
Japanese Patent Provisional Publications No. 62-292780 and No. 63-10756 describe a process for preparing Zaltoprofen which starts from a haloketal compound.
Japanese Patent Provisional Publication No. 63-2970 describes a process for preparing Zaltoprofen in which methyl 5-propionyl-2-phenylthiophenylacetate is reacted with an orthoformic acid ester and metallic zinc or zinc halide to produce methyl 2-(3-methoxycarbonylmethyl-4-phenylthiophenyl)propionate, and this product is employed for the preparation of Zaltoprofen.
As described above, a variety of processes for preparing Zaltoprofen are known. However, more improved processes are desired from the viewpoints of availability of the starting materials and easy handling of the materials participating in the reactions for the preparation, as well as economical viewpoints such as yields.
The present invention has an object to provide new processes for preparing Zaltoprofen.
Specifically, the invention has an object to provide new processes for preparing Zaltoprofen which are advantageously employable in industry from the viewpoints of availability of the starting materials and easy handling of the materials participating in the reactions for the preparation, as well as economical viewpoints such as yields.